Which was already dated by the time the show aired, as "gay" meaning homosexual was the primary use of the word by the early 60s.
Well, among certain groups. It wasn't really until the 70s when the "homosexual" meaning of gay became prevalent over the "happy" one for many people.
Two of the spinoffs from the Flintstones modified that line. "The Flintstones Comedy Hour/Show" proclaimed "We'll have a groovy time" (this was early-1970s), while "The New Fred and Barney Show" sang "We'll have a great old time".
The Late Late Show with Craig Ferguson mentioned this in a Funny Moment. "Well, back then, 'gay' meant fun. Not like now, when it means 'really fun.'"
In an episode of Drawn Together, the cast drives by a devastated Bedrock, and Princess Clara snidely comments "well that's what they get for having a gay old time."
In one episode of Adventures of Sonic the Hedgehog upon hearing that an island was full of "booby traps", Grounder responds with "Booby traps? What does he think we are, boobs?"
Some old Looney Tunes shorts have titles that make you look twice nowadays:
"Puss 'N' Booty" (1943)
"Angel Puss" (1944)
"Bone, Sweet Bone" (1948)
"Boobs in the Woods" (1950)
"Easter Yeggs" (1947) had Bugs encountering a weeping Easter Bunny who explains to him that his job delivering Easter eggs has made his feet sore and thus is unable to continue the job unless another rabbit does it for him (unbeknown to him, the Easter Bunny tricks other rabbits by guilt tripping them to doing the job for him while he doesn't have to do anything). During his sob story, he briefly mentions himself being "happy and gay" before hurting his feet. This can be taken both ways.
The Bugs Bunny cartoon "Bunny Hugged" features The Crusher, a huge beast of a wrestler, and his seriously mismatched opponent, a parody of real-life 'sissy' wrestler Gorgeous George, announced as "Ravishing Ronno - the Gay Nature Boy". Again, can be taken both ways.
Daffy Duck: [to second Daffy] Listen bud, If you wasn't me, I'd smack you right in the puss.
Several old Tom and Jerry shorts have "Puss" or "Pussy" in the title. In one, Spike the bulldog threatened Tom with "I'll poke you in the puss!" Puss has always meant face though, even if it's uncommon nowadays. PussY on the other hand...
In the same vein as Woody himself is Chilly Willy, although that's more for the British.
A Yogi Bear cartoon from the 1960s featured a troop of boy scouts camping at Jellystone Park, and Yogi scheming to get them to "share" their food with him. Ranger Smith sternly reprimands Yogi for this, saying, "Those boy scouts would never molest a bear, and I'm going to make sure that no bear molests them." "Molest" had a meaning closer to "harass" or "upset" back then, but nowadays that line just comes out wrong, and the whole boy scout thing makes it even wronger.
Anyone who does attempt that kind of a thing with a bear probably deserves whatever they get.
Similarly, the 1942 Porky Pig/Daffy Duck short My Favorite Duck has a scene where Daffy points out a sign reading: "Season closed - No duck shooting - Don't even molest a duck".
The Polish translator went with the word "molestowac", which means exclusively "to sexually harass" in modern Polish. Apparently, the translator missed somethingthere. Also, the translator omitted the word "even", which quite clearly points to the fact that "molests" means something mild in this context.
Also, from Yogi's Gang (a sort of team-up of all the Hanna-Barbera talking animals up to that point) theme song, "If those big goons were out of the way / the world would be so bright and gay".
An episode of X-Men: Evolution has Juggernaut boasting that he's raw power. Cyclops responds, "You want it raw, tough guy? Then take it raw!" before ripping off his protective barrier. 'Raw' is becoming more and more recognized as a term for condomless sex.
In one episode of Spider-Man: The Animated Series, a young boy interrupts a crime by shouting "Your gangbanging days are over!" at the perpetrators. In modern parlance "gangbanger" pretty much always means "someone in a street gang", while "gang bang" pretty much always means "group sex". Some derivatives (such as "gangbanging") could go either way, though it's usually pretty clear from context which is meant.
Remember the 'making love' explanation earlier? Does explain how Pepe Le Pew got away with saying he'd love to do this all night and all day with an obviously non-consenting non-skunk he happened to grab without everyone and their senator screaming to bleach out the soundtrack.
Jem features a song called "Who Is He Kissing?" about Jerrica's Two-Person Love Triangle troubles. It features the lyrics "Who is he kissing/Is it me/Or is he making love to a fantasy?" By the mid 1980s "making love" had its modern meaning however, it's likely the only reason it was allowed was due to the fact the lyrics say "Who is he kissing?" and the video shows them kissing several times. In-series there are no implications Jem and Rio have done anything besides kiss either.
A Fractured Fairy Tales segment had the Big Bad Wolf as a lazy cad, reading a popular upscale girlie mag with the slightly altered title "Gay Boy".
In the British cartoon King Arthur's Disasters Lancelot's catchphrase when something happens that he doesn't like is "Oh Blow!"
The 1936 Felix the Cat cartoon "Bold King Cole" had Felix singing this lyric.
Matthew Pocket: Oh, what a gay time we shall have, and I do mean gay as in festive, not as in penetration of the bum.
Also lampshaded: "Chef's Chocolate Salty Balls", which Eric Cartman likes to eat.
"Rainforest Schmainforest" put all three definitions of "gay" to use in various ways. The Getting Gay With Kids choir is all about children spreading cheer and not at all about going pederastic, though one jungle geurilla does rather indignantly declare that "I'm not getting gay with any kids!" Then too, the Getting Gay With Kids choir's original theme is indeed as "totally gay" as it claims to be. (Their revised theme at the end, however, wasn't so gay in any sense of the word.)
Sky Dancers had an episode where one of the main characters had choreographed a new dance, and her companions urged her to demonstrate at a public event. Cue cries of "We want The 'D'! Show us The 'D'!"
The 1954 black and white Frosty the Snowman short has a line "Happy and gay was he". It still airs on TV occasionally.
One of the characters in the Justice Friends segment is Krunk, a parody of The Incredible Hulk. It's a homophone of "crunk", a term developed about a half decade after the show began meaning being drunk and high on cannabis at the same time.
In "Dexter is Dirty", Dexter collides with a giant container full of green stuff labeled "waste spooge". "Spooge" generally referred to any liquid waste, but since then has almost only been used as obscene slang for ejaculation.
Johnny Bravo: In the Schoolhouse Rock parody episode, Jack Sheldon's character sings "Show that girl that you really give a D!", with him handing a large letter D to a smiling woman. Needless to say, this image became quite popular after the phrase "give her the D" entered common usage.
Played for laughs with Mr. Burns (who, according to the show's ever-shifting canon, came of age sometime between the turn of the twentieth century and The Roaring '20s) is apparently completely unaware of the latter-day definition of the word "gay". On one occasion, on a shock-jock radio show, he recalls his father taking him to a picnic when he was a child, saying "That certainly was a gay experience. I ate my share of wieners that day!"
Mr. Burns asks Smithers what he did this weekend, "Something gay, no doubt." Smithers is momentarily taken aback, but Burns continues, "You know, light-hearted, fancy free, mothers, lock up your daughters, Smithers is on the town!" Smithers is visibly relieved.
Smithers is set on fire, and runs by Mr. Burns, who is watering the lawn. Screaming, "Help me, Mr. Burns! I'm flaming!". Cue an Aside Glance that shatters the Fourth Wall.
Burns (to Homer): "You're much more fun than Smithers. He doesn't even know the meaning of the word gay!" (Cue Gilligan Cut that demonstrates that, yeah, he kinda does.)
The season 22 episode "Flaming Moe" (not The One with...Aerosmithnote That one was called "Flaming Moe 's") turns this up to eleven; one of Smithers' "friends" comments upon meeting Burns that he didn't know Smithers was into "lemon parties"note VERY not safe for work, look it up yourself— or, better yet, don't, and Burns obliviously insists that he gets "first squeeze".
Another Martin Prince example had him refer to a humanoid skeleton as "one of the major Homos." Bart was about to let Martin have it for that one, but Lisa stopped him.
Kent Brockman thanking New Springfield for making them rich: "From now on, we'll be taking golden showers!" Which is followed by off-screen laughter from the crew as Brockman asks "What!?"
Unlike when it was aired, "The Telltale Head" may make your kids giggle with Homer's line: "You know, Bart, when I was your age, I pulled a few boners."
The Simpson innuendo for the ages, with a bit of Hypocritical Humor on Ned Flanders's part: "Homer, all of us pull a few boners now and then, go off half-cocked, make asses of ourselves. So I'm not trying to be hard on you, but I just wish you wouldn't curse in front of my boys."
In a storyline in Spider-Man: The Animated Series, Peter is bemused at the idea of a WWII-era hero in a yellow costume called The Whizzer — because of his speed. At Omar Mosely explains, it was a different time.
In Archer, episode "Double Deuce", it's already been established that Woodhouse is attracted to Reggie Thistleton. Both characters are British and fighting in The Great War when this happens:
Woodhouse: I'm a — Reggie: Fag? Woodhouse: Excuse me, sir? Reggie: Have you got one? Dying for a smoke.
Given that Mr. Krabs of SpongeBob SquarePants' entire manner of speech is intentionally archaic, this trope's pretty in-line with his character. The episode "The Lost Mattress" has Mr. Krabs use "queer" in its "strange, unusual" meaning. The episode "The Krusty Sponge" has Mr. Krabs refer to a little boy as a girl. "Girl" once used to mean a little kid, regardless of gender.
The Venture Bros.: In "Everybody Comes to Hank's", a Film Noir homage, Hank starts talking like a Hardboiled Detective whenever he puts on his fedora. He uses so much obsolete slang that even his partner can barely understand him. One of his monologues, about a failed attempt to canvas the neighborhood for leads, is delivered without irony but has Shoreleave sniggering.
Hank: Your basic boob ain't too keen on dicks. When a bum sees a dick coming, he don't stick around for the credits.